The following description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
Traditional techniques of charging batteries are inefficient. In particular, when it pushes a current through a battery, only a small amount of the current (i.e., charge) is retained within the battery while most of it is converted into heat energy. As such, the traditional battery charging techniques can take hours to provide a full charge to a battery or battery pack. They are also limited to charging non-primary (i.e., rechargeable) batteries such as Nickel Metal Hydride (NiMH) batteries or Lithium Ion (Li-Ion) batteries. In addition, once batteries fall below a certain capacity and/or voltage, they are considered “dead” and are not recoverable using the traditional battery chargers that are available on the market.
Efforts have been made to improve the efficiency of battery chargers. For example, pulse charging, in which a series of current pulses is fed to the battery, has been known to be more effective than traditional battery charging techniques. For lead-acid based batteries, the current pulses are also known to break down the sulfation on the plates, which allows the battery to last longer.
With pulse charging, one of the varying factors is the pulse frequency. It is known that batteries usually accept charges most efficiently when being charged with pulses at the batteries' resonant frequencies. U.S. Pat. No. 8,207,707 to Hart et al. issued Jun. 26, 2012, entitled “Method and Apparatus to Provide Fixed Frequency Charging Signals to a Battery At Or Near Resonance” discloses a battery charger with a fixed frequency charging signal at or near the resonant frequency of the battery to be charged.
U.S. Pat. No. 8,120,324 to Fee et al. issued Feb. 2, 2012, entitled “Method and Apparatus to Provide Battery Rejuvenation At Or Near Resonance” also discloses the use of a battery's resonant frequency to rejuvenate the battery that has lost capacity.
While different types of batteries have different resonant frequencies, different charge states of a battery also have slightly different resonant frequencies. International patent publication WO2009/035611 to Fee et al., filed Sep. 12, 2007, entitled “Method and Apparatus to Determine Battery Resonance” discloses a method of determining the resonant frequency of a battery at different charge state so that pulses can be generated at the correct resonant frequency to a battery depending on the battery's charge state.
The above-described techniques have greatly improved the efficiencies of battery charging when compared with traditional charging techniques. Their efficiencies are good enough for charging batteries for small appliances (e.g., AA, AAA batteries). However, existing technologies are still not capable of providing good charge time for large batteries such as electric cars' batteries. For example, Tesla® has reported that its electric car batteries requires four hours to charge from empty to full capacity using a 240 V charger on a 90 A circuit breaker (best scenario) and requires forty-eight hours to charge the same using a 120 V household outlet on a 15 A circuit breaker.
Thus, there is still a need to improve on existing battery charging techniques.
All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, reaction conditions, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.
As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims.